Plate Tectonics and Volcanoes

Misconceptions about VolcanoesStudies show that many middle grade students believe volcanoes are randomly located across the earth’s surface and are found only on land. These students also think volcanoes erupt straight up and erupt violently. They are led to believe that if a volcano doesn’t erupt for a hundred years, it’s extinct.

In some places, continents rub against each other creating earthquake zones. The San Andreas Fault in California is a boundary between the North American plate and the Pacific plate. In these zones, stress builds up in the earth’s interior as the plates rub against each other. Just like winding up a spring, the rocks will continue to strain against each other until eventually they will break and release energy.

As a result of new crust forming at divergent boundaries, plates will collide and form convergent boundaries. The collision of plates will force one plate to go beneath the other and into the mantle. Here it will become liquid magma. If the colliding plates are in the ocean, deep trenches are formed. Volcanic activity can occur along these convergent boundaries as well. Sometimes volcanic mountain ranges will rise higher than those on land and sometimes they will rise above sea-level and form islands. If the plates collide that contain one ocean and one continent, and then mountain chains are usually formed as the continents crumple

The Truth The majority of volcanoes are located along tectonic plate boundaries. “Ring of Fire” is the name given to an area along the border of the Pacific Plate with a high concentration of volcanoes. The Pacific Northwest, Alaska’s Aleutian Islands, and Japan are all located in the Ring of Fire. Volcanoes are found on land and under the ocean’s surface, as well as in areas with cold climates (like Antarctica).

Students may also believe that all volcanic eruptions are violent, but many are not. The levels of silica and dissolved gases in the magma determine whether a volcano erupts explosively or effusively. Magma and gas may escape through cracks and weak areas on the sides of the volcano in addition to the top vent. Baking soda and vinegar models, a staple of elementary school science, do not accurately model an eruption and could lead to the formation of misconceptions.

Ask-A-Geologisthttp://walrus.wr.usgs.gov/ask-a-geologist/

Students may also not understand that volcanoes can be inactive for long periods without being considered extinct. When volcanoes no longer have a lava supply, they are extinct, but it can be quite difficult for scientists to know if and when this is the case. For example, scientists are fairly certain that volcanoes of the Hawaiian Islands chain are extinct. Mount Vesuvius in Italy was believed to be extinct before erupting violently

In divergent boundaries, plates move away from each other. Molten magma rises up in between, cooling, and forming new crust. The Mid-Atlantic Ridge is an example of a divergent boundary. Some divergent boundaries occur beneath continents as well. The Great Rift Valley in East Africa was formed by the separating of two plates.

The Theory of Plate Tectonics explains the movement taking place on the earth’s crust. The earth’s crust is made up of plates that collide and rub against each other as they float on top of boiling rocks. The colliding and bumping of plates cause continents to collide, tear apart, form mountains and volcanoes, and open up basins along their boundaries. Geologists have identified three particular types of boundaries: Divergent, convergent, and neutral

The TruthContinents and oceans sit on plates. Plates move approximately 3 inches a year. Since the mantle convects, it moves rapidly like boiling water. When plates move, their boundaries diverge, converge, or transform to create mountains, ocean trenches, volcanoes, and earthquakes.

What is a Volcano?To a volcanologist, a volcano is a structure of the Earth's crust containing a vent or cluster of vents fed by magma rising directly from great depth within the earth, generally more than 30 km (18 miles).

Misconceptions According to American Association for the Advancement of Science (2013), 50% of students believe that continental plates move and oceanic plates do not. Additional misconceptions include: Students thinking plates move big distances every year instead of just inches. Many also think the mantle moves slowly when it actually moves rapidly like boiling water. A large number of students also believe plates come crashing together like cars in an automobile accident and that these collisions cause earthquakes.